Message-ID: <457D89FE.4040301@nrao.edu>
Date: Mon, 11 Dec 2006 11:40:30 -0500
From: Frank Ghigo <fghigo@nrao.edu>
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To: emomjian@naic.edu, jbraatz@nrao.edu, mbieten@yorku.ca
CC: ccarilli@nrao.edu, bartel@yorku.ca, mrupen@aoc.nrao.edu,
        gbtobssum
 <gbtobssum@donar.cv.nrao.edu>,
        VLB operators <vlbaops@gb.nrao.edu>,
        GBT
 operations <gbtops@gb.nrao.edu>,
        "analysts@aoc.nrao.edu"
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Subject: VLBI: BM253, BB227, BB228 at the GBT
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Over the past few days there were some problems with observing
during some of the VLBI experiments at the Green Bank Telescope.

The GBT was stowed December 9 from 05:24 to 11:50 UT due
to the temperature going below zero Fahrenheit.
Thus the first 3 hours of project BM253A was missed.
Good data on BM253A started at 12:04 UT.

Project BB227A had almost no problems; there was about 15 minutes
lost due to an Astrid hangup at 04:23 to 04:37 UT.

During project BB228B, there were intermittent problems
with the subreflector positioning.
December 10: 19:20 to 19:48 UT - data probably good, but subreflector 
may have sometimes been out of position.
19:48 to 21:24 UT -- antenna stowed -- hardware being diagnosed.
21:26 to 22:50 UT --  data probably good.
22:51 to 00:14 UT -- antenna stowed, problems being worked on.
00:14 UT until the end of the run -- good data.

System temperatures:
BM253A -- about 20 K
BB227A  -- about 50 K
BB228B - - about 50 K

Phase cal levels:
BM253A (at 1.4 GHz)  about 5.5%
BB227A (at 22 GHz) about 1-4%
BB228B (at 22 GHz) about 1-3%

The cable delay measurement was not working; it was stuck
at about 470 ns during these runs.

Weather was mostly clear and cold throughout these observations.

Mark5 disks NRAO-028, NRAO-113, and NRAO-009
are being shipped to Socorro today.

-- frank